You may not be aware of that, but there exist an official ALIEN tabletop RPG. It allows you to play as various characters in the universe of Alien, some time after the events of A3.
Personally I dislike it, since I don't enjoy player characters' aspects, but its otherwise quite enjoyable game, offering many interesting possibilities to engage in and expand the setting. It also features sweet graphical design.
To date, there has been no official, licensed ttRPG taking place in the universe of Aliens. The tactical combat game you linked, the Colonial Marines Manual, the Fuzion-based fanmade rpg (and some other fan projects), the boardgames - they have been made but they didn't offer full rpg experience comparable to the one I linked here.
This is - for good and bad - the only official ttRPG there is.
Personally, I'm a bit disappointed with it, and would rather use the setting and lore included + different ruleset (even some other 2d20-based games are more interesting in my opinion).